Study of the Mechanisms Driving Land Use/Land Cover Change and Water Yield in the Ganjiang River Basin Based on the InVEST-PLUS Model

Water yield is a critical component of hydrological ecosystem services, influenced by both natural environments and human activities. Changes in land use and land cover (LULC) are particularly pivotal in causing water yield variations at the basin level, particularly for the ecologically fragile Ganjiang River Basin (GRB) in southern Jiangxi province, China. Over the last 33 years, the GRB has undergone substantial LULC changes that have significantly affected its water yield. Initially, this study assessed water yield from 1990 to 2022 using the InVEST model, then predicted future LULC scenarios using the PLUS model, including natural development (ND), cropland protection (CP), ecological protection (EP), and urban development (UD). The Geodetector model was then employed to analyze the influence of various factors on water yield changes. Key findings include the following: (1) Significant landscape changes were observed, including increases in impervious surfaces, cropland, and water areas, accompanied by substantial reductions in forest and other natural lands. The most pronounced decline occurred in forested regions. (2) The total water yield decreased by 0.44 × 1010 m3 over the study period, exhibiting fluctuations until 2016 and stabilizing afterward. Water yield was generally higher in the northeast and lower in the southwest, primarily influenced by actual evapotranspiration, LULC, and precipitation. (3) The impact of LULC changes on water yield varied by scenario, with the scenarios ranked from most to least impactful as follows: UD, ND, CP, EP. This variation is mainly due to the different rates of evapotranspiration and infiltration associated with land cover. These insights are crucial for guiding policymakers in developing effective LULC strategies that promote ecological restoration and sustainable water management in the basin.